Due to an increasing number of wireless devices and a growing demand for wireless services, wireless communication systems continue to expand. To meet the growing demand, and to increase interoperability and reduce costs, various sets of standards have been introduced for wireless communications. One such set of standards developed for wireless communication is IEEE 802.16. IEEE 802.16 includes the family of standards developed by the IEEE 802.16 committee, establishing standards for broadband wireless access. In part, the IEEE 802.16 family of standards defines interoperability of broadband Wireless Metropolitan Area Networks (WirelessMAN). Generally speaking, WirelessMANs are typically large networks utilizing wireless infrastructure to form connections between subscriber stations. Wi-Max, a term defined and promoted by The Wi-Max Forum™, is commonly used to refer to WirelessMANs and wireless communication and communication networks that are based on the IEEE 802.16 standard. As used herein, the term “Wi-Max” refers to any communication network, system, apparatus, device, method, etc. that utilizes or is based on the 802.16 family of standards.
IEEE 802.16e supports Quality of Service (QoS) by providing various service classes to services with different characteristics. The service classes in IEEE 802.16e have been designed to support real-time applications such as voice and video and non-real-time application such as large file transfer. Different kinds of traffic supported by an IEEE 802.16e network are classified into one of the following services: (1) Unsolicited Grant Service (UGS) (2) Real-time Polling Service (RT-VR) (3) Extended Real-time Service (ERT-VR) (4) Non-Real-time Polling Service (NRT-VR) and (5) Best Effort Service (BE).
The standard provides specifications for these different services, but does not specify any scheduling architecture. QoS support in wireless networks is a more difficult task than in wired networks, because the characteristics of a wireless link are variable and unpredictable. To cope with the unpredictability, QoS in wireless networks is usually managed at the medium access control (MAC) layer. In addition to scheduling, a Power Saving Mode (PSM) is also a part of IEEE 802.16e. A PSM provides energy savings on a mobile station when the traffic load is low. PSM consists of alternating sleep intervals and listen intervals. Generally, during the sleep interval the device cuts off all contact with its serving base station and saves its energy. During the listening interval, the device waits for traffic or sends packets out. The procedure of sleep mode described in IEEE 802.16e consists of grouping connections according to their QoS types to create Power Saving Classes (PSCs).
In this regard, IEEE 802.16 enumerates three kinds of Power saving classes:                Power Saving Class I (PSC I): Groups NRT-VR and BE connections        Power Saving Class II (PSC II): Groups UGS, ERT-VR and RT-VR connections        Power Saving Class III (PSC III): Groups multicast connections and management connections        
Each type of PSC has a set of message exchange procedures for its definition/activation/deactivation. Moreover, IEEE 802.16e defines a general set of parameters and rules that can be used to design their different windows. For the specific case of PSC I there is a proposed formula for calculating sleep window size according to traffic presence.
However, there is a need to define a robust, QoS-aware and efficient method of scheduling and power savings. Without efficient scheduling there is no guarantee of QoS and throughput is compromised and, without a robust PSM, energy saving may be not optimal.
The IEEE 802.16e standard proposes a general concept of design and maintenance of Power Saving Classes, without any in-depth description.
The disclosed embodiments are directed to overcoming one or more of the problems set forth above.